1. Field of the Invention
The present invention relates to a support instrument with an intramedullary nail and, more particularly, to a support instrument with a modular intramedullary nail able to adjust the number of modular intramedullary nails according to dimensions of the medullary cavity of a bone.
2. Description of the Related Art
Generally, the way to treat a patient with a fractured long bone is to insert an intramedullary nail into its medullary cavity to bridge a defect of the fractured long bone for the bone to re-grow and recover in a short period of time.
Referring to FIG. 1, a conventional intramedullary nail disclosed by a Taiwan Patent titled as “Improved Structure of Bone Medulla Internal Nail” with Publication No. 471306 is shown and numbered as “9.” The intramedullary nail 9 is in a form of a curved cylinder with an adjusting device 91 for adjustment in a position of the intramedullary nail 9 relative to a medullary cavity wherein the intramedullary nail 9 is disposed. Thus, a defect of a deficient bone having the medullary cavity is provided with stabilization and reinforcement, and the deficient bone can re-grow and recover in a short period of time. When the intramedullary nail 9 is used, a hole communicating with the medullary cavity has to be formed at an end of the deficient bone for the intramedullary nail 9 to be inserted into the medullary cavity. Then screws 92 are used to respectively fix two ends of the intramedullary nail 9 in the medullary cavity firmly.
However, with this kind of intramedullary nail 9, hospitals have to prepare and store intramedullary nails 9 in various sizes for patients with different builds or affected parts since the dimensions of every single intramedullary nail 9 are constant. Therefore, the conventional intramedullary nail 9 may lead to difficulty in reserve management for the hospitals and manufacturers.
Due to the above drawback of the intramedullary nail 9, some other kinds of intramedullary nails, such as the one disclosed by a Taiwan Patent titled as “Multi-Staged Internal Locking Type Internal-Bone Nailing Device” with Publication No. 588643 and shown in FIG. 2, are proposed. Referring to FIG. 2, the intramedullary nail numbered as “8” includes a distal end fixer 81, at least one mid rod 82, and a base end fixer 83. The distal end fixer 81 has a connector 811, with each of the mid rods 82 having two connectors 821 at two ends thereof, and the connectors 811, 821 able to couple with each other. The connector 811 of the distal end fixer 81 is coupled with a connector 821 of a mid rod 82, and the other connector 821 of the mid rod 82 is coupled with the base end fixer 83 or a connector 821 of another mid rod 82. Thus, the intramedullary nail 8 constructed by the distal end fixer 81, at least one mid rod 82, and base end fixer 83 can provide a variable length by changing the number of the at least one mid rod 82. As a result, the length of the intramedullary nail 8 can be adjusted during operation of the deficient bone. Therefore, the reserve management for the intramedullary nail 8 is easy since sizes of the mid rods 82 constructing most parts of the intramedullary nail 8 are identical.
Nevertheless, the connectors 811, 821 of the intramedullary nail 8 easily become structural weaknesses when the intramedullary nail 8 is inserted inside the medullary cavity. Besides, since both of the distal end fixer 81 and mid rod 82 are in the form of a straight cylinder, the curvature of the intramedullary nail 8 is limited and the intramedullary nail 8 may not perfectly fit the medullary cavity when the straight cylinder is too long. Alternately, there may be too many structural weaknesses formed by the connectors 821 when the straight cylinder is too short.
Moreover, a diameter of the cross-sectional view of the intramedullary nail 8 is still unchangeable although the intramedullary nail 8 is an assembly of the distal end fixer 81, at least one mid rod 82, and base end fixer 83. Furthermore, an added or reduced length of the intramedullary nail 8 can only be a multiple of the length of the mid rod 82, which may result in a total length of the intramedullary nail 8 over a suitable length for the medullary cavity. In this situation, only drawing out bone medulla to deepen the medullary cavity for the intramedullary nail 8 is an effective way, and this operation may further hurt the patient.
In light of this, it is desired to improve the conventional intramedullary nail.